JP2017532192A - Titania-doped zirconia as a platinum group metal support in catalysts for treating exhaust gas streams of combustion engines - Google Patents

Abstract

Mixed metal oxide composites for exhaust gas purification catalysts include co-precipitated materials of the following composites: zirconia in amounts ranging from 55 to 99% by weight, titania in amounts ranging from 1 to 25% by weight. , Promoters and / or stabilizers in amounts ranging from 0 to 20% by weight. These composites are useful as supports for platinum group metals (PGM), particularly rhodium.

Description

TECHNICAL FIELD The present invention relates to a mixed metal oxide support for an exhaust gas purification catalyst and a method for using the same. More particularly, a titania-doped zirconia support for platinum group metals (PGM) is provided. Specifically, a titania-zirconia support optionally added with a co-catalyst such as Lantana or a stabilizer is excellent in three-way conversion (TWC: Three Way Conversion) ) Supports rhodium which provides catalytic activity.

Background Emission standards for pollutants of unburned hydrocarbons, carbon monoxide and nitrogen oxides are becoming stricter. In order to satisfy these standards, a catalytic converter including a three-way conversion (TWC) catalyst is arranged in the exhaust gas line of the internal combustion engine. Such catalysts not only promote the oxidation of unburned hydrocarbons and carbon monoxide with oxygen in the exhaust gas stream, but also promote the reduction of nitrogen oxides to nitrogen. Government regulations (eg, LEVIII in the US and Euro 6 & 7 in Europe) cover emissions from the cold start until the catalyst is fully warmed. A strategy to address this is to ensure that the PGM is supplied by a support that does not interfere with the platinum group metal (PGM) at low temperatures and that improves its performance.

  A catalyst having lanthanide-doped zirconia as a support for TWC applications is shown in US Patent Application Publication No. 2013/0115144 (U.S. Patent Appln. Pub. No. 2013/0115144). WO 9205861 (WO9205861) describes a co-generated ceria-zirconia composite to be used to support rhodium, where a base metal oxide is co-deposited on a support having rhodium as a cocatalyst. Can be distributed.

  There is a continuing need in the art to provide catalyst products that provide superior catalytic activity and / or light-off performance and / or efficient use of components to achieve regulated emissions.

SUMMARY OF THE INVENTION A mixed metal oxide composite for an exhaust gas purification catalyst, a method for its production and its use are provided. These composites are useful as supports for platinum group metals (PGM), particularly rhodium.

  A first embodiment comprises zirconia in an amount in the range of 55-99% by weight, titania in an amount in the range of 1-25% by weight, co-catalyst and / or stabilizer in an amount in the range of 0-20% by weight, A mixed metal oxide composite for an exhaust gas purifying catalyst is provided. The cocatalyst comprises a rare earth metal oxide and is present in an amount ranging from 0.1 to 20%. The cocatalyst may include lantana, tungsta, ceria, neodymia, gadolinia, yttria, praseodymia, samaria, hafnia, or combinations thereof. The stabilizer is present in an amount ranging from 0.1 to 5% and may include silicon oxide. Stabilizers are present in amounts ranging from 0.1 to 10% and may include alkaline earth metal oxides. The ceria content of the composite may be 20% by weight or less, or 10% by weight or less, or 5% by weight or less, or 1% by weight or less, or 0.1% by weight or less, or even 0% by weight.

  The composite may include co-precipitated zirconia, titania, and cocatalyst and / or stabilizer. Alternatively, the composite may include zirconia and a cocatalyst and / or stabilizer in a co-precipitated state, where the titania is impregnated from the titania precursor. The titania precursor may comprise a titanium salt, a titanium-containing organic complex, a titania sol, or a colloidal titania.

The composite may have a surface area in the range of 10-40 m ² / g after aging in a furnace at 1000 ° C. for 12 hours.

  Another aspect of a combustion engine includes a catalytic material on a support, the catalytic material comprising a platinum group metal (PGM) supported on any of the mixed metal oxide composites disclosed herein. A catalyst composite for treating an exhaust gas stream is provided. The catalyst composite may contain rhodium in an amount ranging from 0.1 to 5% by weight. The catalyst composite can have a mass ratio of titania to rhodium in the range of 5 to 250. The catalyst composite may contain 0.25% by weight rhodium, which is a conversion of carbon monoxide and nitrogen oxides of 50% or more after aging at 950 ° C .; and dilute overconcentrated lambda at 300 ° C. It is effective to provide a hydrocarbon conversion of 10% or more with a lambda in the range of 0.98 to 1.02 during the sweep test.

  In a further aspect, a system for treating an exhaust gas stream comprising hydrocarbons, carbon monoxide and nitrogen oxides of an internal combustion engine includes an exhaust pipe in fluid communication with the internal combustion engine via an exhaust manifold; and disclosed herein. Optional catalyst composites.

  In another aspect, a method for treating exhaust gas includes contacting a gas stream comprising hydrocarbons, carbon monoxide, and nitrogen oxides with any of the catalyst composites disclosed herein. The mixed metal oxide composite comprises zirconia in an amount in the range of 55-90% by weight; titania in an amount in the range of 5-25% by weight; lanthanum oxide in an amount in the range of 5-20% by weight. The platinum group metal may contain a catalyst and the rhodium in an amount of 0.25% by weight; and after aging at 950 ° C., the catalyst composite has a carbon monoxide and nitrogen oxide conversion of 50% or more. And can be effective to provide hydrocarbon conversions of 10% or more at lambda in the range of 0.98 to 1.02 during a lean overconcentrated lambda sweep test at 300 ° C.

  Also, obtaining or forming a first aqueous solution of a salt of zirconium, a salt of a metal promoter, and optionally a stabilizer salt; obtaining or forming a second aqueous solution of a salt of titanium; first aqueous solution and second Mixing with aqueous solution; and coprecipitation of zirconia, optional promoter or stabilizer metal, and titania under basic conditions, thereby forming a coprecipitated mixed metal oxide composite. A method of manufacturing a mixed metal oxide composite is also provided. The method may further include drying and calcining the co-precipitated mixed metal oxide composite.

  Also obtain co-precipitated zirconia and metal promoter and optional stabilizer; obtain an aqueous solution of titanium precursor; impregnate titanium precursor with co-precipitated zirconia and metal promoter; There is also provided a method of making a mixed metal oxide composite comprising forming a metal oxide composite.

  The present disclosure may be more fully understood in view of the following detailed description of various embodiments of the disclosure in connection with the accompanying drawings.

FIG. 1 shows a graph of carbon monoxide (CO) conversion to lambda at 300 ° C. FIG. 2 shows a graph of hydrocarbon (HC) conversion to lambda at 300 ° C. FIG. 3 shows a graph of nitrogen oxide (NO) conversion to lambda at 300 ° C. FIG. 4 shows a graph of hydrocarbon (HC) conversion to lambda at 350 ° C. FIG. 5 shows a graph of carbon monoxide (CO) conversion to lambda at 350 ° C.

DETAILED DESCRIPTION OF THE INVENTION Mixed metal oxide composites are used as a support for zirconia in amounts ranging from 55 to 99% by weight; titania in amounts ranging from 1 to 25% by weight; platinum group metals (PGM). An effective amount of co-catalyst and / or stabilizer in the range of 0-20%. The washcoat is coated on a carrier used as a catalyst composite or article for processing downstream of a combustion engine, eg, an automobile engine, on which PGM, particularly rhodium, is supported.

  The following definitions are used herein.

A platinum group metal (PGM) component refers to any compound comprising PGM. For example, the PGM may be in metal form, i.e., zero valance, or in the form of an oxide. Referring to the PGM component, any valence state PGM can exist. For example, rhodium can be present in Rh ⁰ and / or Rh ³⁺ , or other oxidation states.

“BET surface area” has the usual meaning of referring to a specific surface area measurement method (Brunauer-Emmett-Teller method) in which the surface area is measured by N ₂ adsorption measurement. Unless otherwise stated, “surface area” refers to BET surface area.

  “Support” in a catalyst material or catalyst washcoat refers to a material that receives noble metals, stabilizers, cocatalysts, binders, etc., through precipitation, association, dispersion, impregnation, or other suitable method. A composite of zirconia, titania, and optionally mixed metal oxides including cocatalysts and / or stabilizers is useful as a support. Examples of other supports include refractory metal oxides, including high surface area refractory metal oxides, composites containing oxygen storage components, and mixed metal oxides disclosed herein, It is not limited to these.

  “Transition metal oxide” (TMO) refers to one or more oxides of metals of Groups 3-12 of the Periodic Table of Elements.

  “Refractory metal oxide supports” include bulk alumina, ceria, zirconia, titania, silica, magnesia, neodymia, and other materials are known for such use. Such materials are believed to impart durability to the resulting catalyst.

The “high surface area refractory metal oxide support” specifically means support particles having pores larger than 20 mm and a wide pore distribution. High surface area refractory metal oxide supports, such as alumina support materials, also referred to as “gamma alumina” or “activated alumina”, typically exceed 60 square meters per gram (“m ² / g”). Often exhibit a BET surface area of the new material of about 200 m ² / g or more. Such activated alumina is usually a mixture of alumina γ and δ phases, but may also contain significant amounts of eta, kappa, and theta alumina phases.

  “Rare earth metal oxide” refers to one or more oxides of the scandium, yttrium, and lanthanum series as defined in the periodic table of elements. The rare earth metal oxide can be both an exemplary oxygen storage component and a promoter material. Examples of suitable oxygen storage components include ceria, praseodymia, or combinations thereof. Delivery of ceria can be achieved, for example, by using ceria, mixed oxides of cerium and zirconium, and / or mixed oxides of cerium, zirconium, and other rare earth elements. Suitable cocatalysts include one or more non-reducing properties of one or more rare earth metals selected from the group consisting of lanthanum, tungsten, cerium, neodymium, gadolinium, yttrium, praseodymium, samarium, hafnium, and mixtures thereof. An oxide is mentioned.

  “Alkaline earth metal oxide” refers to a Group II metal oxide which is an exemplary stabilizer material. Suitable stabilizers include one or more non-reducing metal oxides wherein the metal is selected from the group consisting of barium, calcium, magnesium, strontium and mixtures thereof. Preferably, the stabilizer comprises one or more oxides of barium and / or strontium.

  A “washcoat” is a thin, adherent coating of a catalyst or other material applied to a refractory substrate, such as a honeycomb flow through a monolith substrate or filter substrate, which is the gas stream being processed. It is sufficiently porous to allow passage. Accordingly, a “wash coat layer” is defined as a coating consisting of support particles. The “catalyzed washcoat layer” is a coating composed of support particles impregnated with a catalyst component.

Mixed Metal Oxide Support Material Ti-La-ZrO ₂ support material is prepared as follows. One exemplary method is to co-precipitate the desired components: titanium and zirconium and any desired promoter. Another exemplary method includes providing a co-precipitated zirconia composite (excluding Ce-Zr, for example, a La-ZrO _2), is then be impregnated with a titanium precursor.

A coprecipitate of all desired materials is prepared by preparing two solutions. The first aqueous solution contains a salt of a zirconium salt (for example, zirconium nitrate). The second aqueous solution includes a lanthanum salt (eg, lanthanum nitrate) and a titania precursor. The solution was added to an aqueous solution of ammonia (NH ₃ ) and the mixture was kept at a pH of about 9.0. The filtrate is obtained by drying and treating with an acid such as lauric acid. Further, the filtrate is washed, dried, and fired to obtain a desired composite material. Zirconia is generally present in an amount in the range of 55-99% by weight and titania is present in an amount in the range of 1-25% by weight; optionally in the range of 0-20% by weight of promoter and / or stabilizer. Will be present in the amount of.

  Alternatively, the composite material can also be made by impregnating a titania precursor (titanium compound or titania sol) onto a high surface area co-precipitated La stabilized zirconia composite.

The support material can be characterized in a number of ways. For example, the crystalline form of titanium can be determined by X-ray diffraction (XRD). The surface area of the new support material can be in the range of 60-90 m ² / g. The aged support material may have a surface area in the range of 10-40 m ² / g after aging in a furnace at 1000 ° C. for 12 hours. The mass ratio of titania to rhodium can be in the range of 5-250.

Catalyst Material The catalyst material is prepared as follows. Desired platinum group metal (PGM) are prepared by methods known in the art, for example, it is carried on the Ti-La-ZrO ₂ support by impregnation incipient wetness.

Catalyst Composite Once the catalyst material is prepared, the catalyst composite can be prepared in one or more layers on a support. A dispersion for any of the catalyst materials described herein can be used to form a slurry for a washcoat.

  Any desired additional components may be added to the slurry, such as other platinum group metals, other supports, other stabilizers and cocatalysts, and one or more oxygen storage components.

In one or more embodiments, the slurry is acidic and has a pH of about 2 to less than about 7. The pH of the slurry may be lowered by adding a suitable amount of an inorganic or organic acid to the slurry. The combination of both can be used when the compatibility of the acid and the raw material is taken into consideration. Inorganic acids include, but are not limited to nitric acid. Examples of organic acids include, but are not limited to, acetic acid, propionic acid, oxalic acid, malonic acid, succinic acid, glutamic acid, adipic acid, maleic acid, fumaric acid, phthalic acid, tartaric acid, citric acid, and the like. Thereafter, water-soluble or water-dispersible compounds of oxygen storage components such as cerium-zirconium composites, stabilizers such as barium acetate, and promoters such as lanthanum nitrate can be added to the slurry as needed. Thereafter, when the slurry is pulverized, substantially all solids having an average diameter of less than about 20 microns, ie, a particle size of about 0.1 to 15 microns, are obtained. Grinding may be performed in a ball mill or other similar equipment, and the solids content of the slurry may be, for example, about 10-50% by weight, more specifically about 10-40% by weight. The support is then dipped one or more times in such a slurry, or the slurry is a washcoat / metal oxide composite having a desired loading, eg, about 0.5 to about 3.0 g / in ^3. It can be coated on the support such that the material is deposited on the support.

  The coated carrier is then calcined, for example, by heating at 500 ° C. to 600 ° C. for about 1 hour to about 3 hours.

  Typically, where a platinum group metal is desired, the metal component is a compound or complex to achieve dispersion of components on the refractory metal oxide support, such as activated alumina or ceria-zirconia composite. Used in form. For purposes herein, the term “metal component” means any compound, complex, etc. that decomposes or converts to a catalytically active form, usually a metal or metal oxide, upon calcination or use thereof. To do. A metal or compound thereof or a complex thereof or other component that may be present in the catalyst composition and that can be removed from the metal component by volatilization or decomposition upon heating and / or application of vacuum, and a refractory metal oxide support Water soluble compounds or water dispersible compounds or metal component complexes may be used as long as the liquid medium used to impregnate or deposit the metal component on the body particles does not react adversely. In some cases, the removal of liquid may not be completed until the catalyst is used and exposed to the high temperatures encountered during operation. Generally, an aqueous solution of a soluble compound or a noble metal complex is used from the viewpoints of both economy and environment. During the calcination process, or at least during the initial stages of use of the composite, such compounds are converted to the metal or a catalytically active form of the compound.

  Additional layers can be prepared and deposited on the previous layer in the same manner as described above to deposit any layer on the support.

Support In one or more embodiments, the catalyst material is disposed on the support.

  The support may be any of those materials typically used to prepare catalyst composites and preferably will include a ceramic or metal honeycomb structure. Any suitable carrier (honeycomb flow-through substrate, such as a monolithic substrate of the type in which a fine and parallel gas channel passes through from the inlet or outlet surface of the substrate so that the channel flows in fluid. Can be used). A flow path that is a substantially straight path from the inlet to the outlet is defined by a wall that is coated with the catalytic material as a washcoat, and the gas flowing through the flow path contacts the catalytic material. The flow path of the monolithic substrate is a thin-walled channel that can be any suitable cross-sectional shape and size, such as trapezoidal, rectangular, square, sinusoidal, hexagonal, elliptical, circular, and the like. Such a structure may contain from about 60 to about 900 or more gas inlet openings (ie, cells) per square inch of cross section.

  The carrier may be a wall flow filter substrate in which the channels are alternately blocked, where the gas flow enters the channel from one direction (inlet direction) and flows through the channel wall in the other direction (outlet direction). ) To leave the channel. The dual oxidation catalyst composition can be coated on a wall flow filter. If such a carrier is utilized, the resulting system will be able to remove particulate matter along with gaseous contaminants. The wall flow filter carrier can be made from materials commonly known in the art, such as cordierite or silicon carbide.

  The carrier can be any suitable refractory material such as cordierite, cordierite-alumina, silicon nitride, zircon mullite, spojumen, alumina-silica magnesia, zircon silicate, sillimanite, magnesium silicate, zircon, petalite, alumina, and It can be made of aluminosilicate or the like.

  Supports useful for the catalysts of the present invention may be metallic in nature or may be composed of one or more metals or metal alloys. Metallic carriers can be used in various forms such as corrugated plates or monolithic forms. Preferred metal supports include not only refractory metals and metal alloys such as titanium and stainless steel, but also other alloys in which iron is a substantial or major component. Such alloys may contain one or more of nickel, chromium and / or aluminum, and the total amount of these metals is advantageously at least 15% by weight of alloy, for example 10-25% by weight. It may contain chromium, 3-8% aluminum, up to 20% nickel. The alloy may include one or more other metals, such as manganese, copper, vanadium, titanium, etc., in small or trace amounts. The surface of the metallic support can be oxidized at high temperatures, eg, 1000 ° C. or higher, to improve the corrosion resistance of the alloy by forming an oxide layer on the surface of the support. Such high temperature induced oxidation can enhance the adhesion of the refractory metal oxide support and the catalytically promoted metal component to the support.

  In another embodiment, one or more catalyst compositions may be deposited on an open cell foam substrate. Such substrates are well known in the art and are typically formed of a refractory ceramic or metallic material.

  Before describing some exemplary embodiments of the present invention, it is to be understood that the present invention is not limited to the details of construction or process steps set forth in the following description. The invention is capable of other embodiments and of being practiced in various ways. In the following, preferred designs are provided comprising combinations as described, used alone or in unlimited combinations, the use comprising catalysts, systems and methods of other aspects of the invention.

Embodiments Various embodiments are listed below. It will be understood that the embodiments listed below can be combined with all aspects and other embodiments according to the scope of the present invention.

  Embodiment 1 is a mixed metal oxide composite for an exhaust gas purification catalyst comprising zirconia, titania, and a cocatalyst and / or stabilizer.

  Embodiment 2 provides a combustion engine exhaust gas stream comprising a catalytic material on a support, wherein the catalytic material comprises a platinum group metal (PGM) supported on any of the mixed metal composites disclosed herein. It is a catalyst composite for processing.

  Embodiment 3 includes hydrocarbons, carbon monoxide, and nitrogen oxides of an internal combustion engine, including an exhaust pipe in fluid communication with the internal combustion engine via an exhaust manifold; and any catalyst composite disclosed herein Is a system for treating an exhaust gas stream comprising

  Embodiment 4 is an exhaust gas treatment method comprising contacting a gas stream comprising hydrocarbons, carbon monoxide, and nitrogen oxides with any of the catalyst composites disclosed herein.

  Embodiment 5 provides or forms a first aqueous solution of a salt of zirconium, a salt of a metal promoter, and optionally a stabilizer salt; obtains or forms a second aqueous solution of a salt of titanium; And the second aqueous solution; and co-precipitating the zirconium, the optional promoter or stabilizer metal, and the titanium under basic conditions; thereby a composite metal oxide co-precipitated A method of producing a mixed metal oxide composite comprising forming a material.

  Embodiment 6 provides co-precipitated zirconia and metal promoter and optional stabilizer; obtaining an aqueous solution of titanium precursor; impregnating the co-precipitated zirconia and metal promoter with the titanium precursor A method for producing a mixed metal oxide composite comprising forming a co-precipitated mixed metal oxide composite.

  Embodiments 1-6 herein may each have the following design features alone or in combination.

  The mixed metal oxide composite comprises zirconia in an amount ranging from 55 to 99% by weight; titania in an amount ranging from 1 to 25% by weight; a co-catalyst and / or stabilizer in an amount ranging from 0 to 20% by weight. Can be included.

  The cocatalyst contains the rare earth metal oxide and is present in an amount ranging from 0.1 to 20%.

  The cocatalyst may include lantana, tungsta, ceria, neodymia, gadolinia, yttria, praseodymia, samaria, hafnia, or combinations thereof.

  The stabilizer is present in an amount ranging from 0.1 to 5% and may include silicon oxide.

  Stabilizers are present in amounts ranging from 0.1 to 10% and may include alkaline earth metal oxides.

  The ceria content of the mixed metal oxide composite is 20% by weight or less, or 10% by weight or less, or 5% by weight or less, or 1% by weight or less, or 0.1% by weight or less, or even 0% by weight. It can be.

  The mixed metal oxide composite may include zirconia, titania, and promoters and / or stabilizers, all in a co-precipitated state.

  The mixed metal oxide composite may include zirconia and a co-catalyst and / or stabilizer in a co-precipitated state, where the titania is impregnated from the titania precursor.

  The titania precursor may comprise a titanium salt, a titanium-containing organic complex, a titania sol, or a colloidal titania.

The mixed metal oxide composite may have a surface area in the range of 10-40 m ² / g after aging in a furnace at 1000 ° C. for 12 hours.

  The catalyst composite contains rhodium in an amount in the range of 0.1 to 5% by weight, and the weight% is based on the total weight of the composite.

  The catalyst composite can have a mass ratio of titania to rhodium in the range of 5 to 250;

  The catalyst composite may contain 0.1 wt% to 5 wt% rhodium, such as 0.25 wt% rhodium, which is 50% or more of carbon monoxide, nitrogen oxides after aging at 950C, And hydrogen conversion; and effective in providing a hydrocarbon conversion of greater than 10% at lambda in the range of 0.98 to 1.02 during the lean overconcentrated lambda sweep test at 300 ° C.

  The mixed metal oxide composite comprises zirconia in an amount in the range of 55-90% by weight; titania in an amount in the range of 5-25% by weight; lanthanum oxide in an amount in the range of 5-20% by weight. The catalyst may include a platinum group metal containing rhodium in an amount of 0.25% by weight; and after aging at 950 ° C., the catalyst composite may contain 50% or more of carbon monoxide, nitrogen oxides and hydrogen. Conversion; and can be effective in providing a hydrocarbon conversion of greater than 10% with a lambda in the range of 0.98 to 1.02 during a lean overconcentrated lambda sweep test at 300 ° C.

  The method may further include drying and calcining the co-precipitated mixed metal oxide composite.

Examples The following non-limiting examples will serve to illustrate various embodiments of the present invention. In each example, the carrier was cordierite.

Example 1
Transition metal oxides include 5% lanthana as a 5% titania (TiO ₂₎ and stabilizer / dopant as (TMO), and Zanbun exemplary mixed metal oxide is zirconia (main component) (Ti- la-ZrO ₂₎ was prepared as follows. An aqueous solution of zirconium nitrate was prepared and Solution 1 was made. A lanthanum nitrate aqueous solution was prepared, and a titania precursor (Ti- (V) -ethoxide) was added thereto to obtain a solution 2. Solutions 1 and 2 were added to aqueous ammonia (NH ₃ ) solution and the mixture was held at mixing conditions for 15 minutes at a pH of about 9.0. The mixture was divided and dried at 150 ° C. for 12 hours in an autoclave. Lauric acid was added to increase the surface area of the final product. A filtrate was obtained using a filter, which was then washed with ammonia (25% solution) to remove nitrate. The filtrate was then dried at 40 ° C. and calcined at 700 ° C.

The composite was tested for surface area using the BET method. The surface area of the new composite was 70 m ² / g, and the surface area of the aged composite (12 hours at 1000 ° C., aged in the furnace) was 15 m ² / g.

Example 2
For Comparative Example Comparative composite of 10% by weight of lanthana and 90% by weight of zirconia (La-ZrO _2), it was prepared in the same way as Ti-La-ZrO ₂ composite material of Example 1. The surface area of the comparative composite was tested using the same test method used in Example 1. The comparative composite had a new surface area of 83 m ² / g, and the aged composite (12 hours at 1000 ° C., aged in the furnace) had a surface area of 25 m ² / g.

Example 3
A catalyst material comprising rhodium (Rh) supported on the Ti—La—ZrO ₂ composite of Example 1 was prepared. Specifically, a 0.25 wt% nitric acid Rh solution was impregnated on the composite using a standard incipient wetness method. This material was dried at 120 ° C. and then calcined in air at 550 ° C. for 1 hour. For the test, the catalyst material is slurried with zirconium acetate (5% by weight based on composite), dried under stirring, calcined in air at 550 ° C. for 2 hours, and crushed / sieved to 250-500 μm. Was molded by. The molded catalyst material was aged at 950 ° C. for 5 hours in 10% water under a dilute overconcentration cycle.

Example 4
Comparative Example A comparative catalyst material containing rhodium (Rh) supported on the La—ZrO ₂ composite of Comparative Example 2 was prepared. Specifically, a 0.25 wt% nitric acid Rh solution was impregnated on the composite using a standard incipient wetness method. This material was dried at 120 ° C. and then calcined in air at 550 ° C. for 1 hour. For the test, the catalyst material was slurried with zirconium acetate (5% by weight based on composite), dried under stirring, calcined in air at 550 ° C. for 2 hours, and ground / sieved to 250-500 μm Molded by doing. The molded catalyst material was aged at 950 ° C. for 5 hours in 10% water under a dilute overconcentration cycle.

Example 5
Testing The aged catalyst materials of Example 3 and Comparative Example 4 were tested at different temperatures (250 ° C, 300 ° C, 350 ° C and 450 ° C) under a lambda sweep protocol. The conditions were as follows: GHSV = 70000 h ⁻¹ (standardized to 1 mL of coated catalyst) and vibration feed (λavg ± 0.05, 1 second dilute, 1 second overdense, 180 seconds / position).

At 300 ° C., the catalyst material using the Ti—La—ZrO ₂ composite of Example 1 exhibited superior performance compared to the catalyst material using the commercially available La—Zr composite. At higher temperatures, the performance of the various catalyst materials was not significant. In order to reduce emissions during cold start and improve light-off performance, an execution performance of 350 ° C. to less than 400 ° C. is desirable. 1 to 3 show the conversion rates of the catalyst material emissions (carbon monoxide (CO), hydrocarbon (HC), and nitrogen oxide (NO)) of Example 3 and Comparative Example 4 at 300 ° C.

Example 6
A formulated autocatalyst composite comprising a catalyst material having two layers on a support was prepared. The total noble metal loading was 60 g / ft ³ and the Pt / Pd / Rh ratio was 0/55/5. The cell density of the substrate was 600 cells / in 2 and the wall thickness was about 4 mils (or 101.6 μm). The size of the substrate is 4.66 × 3 inches, volume was 51.17in ^3.

The lower layer deposited on the support contained palladium (Pd), a portion of which was supported by a ceria-zirconia oxygen storage component (OSC) and another portion supported by a high surface area gamma-alumina support. The lower layer also contained a barrier and zirconia. The load of the lower layer was 2.332 g / in ³ .

The upper layer deposited on the lower layer contains rhodium (Rh) on the support, which is 5% TiO impregnated on commercially available La-ZrO ₂ having a Lantana content of 9% by weight. ₂ was included. The load on the upper layer was 1.403 g / in ³ .

Example 7
Comparative Example A comparative formulated autocatalyst composite comprising a catalyst material having two layers on a support was prepared. The total noble metal loading was 60 g / ft ³ and the Pt / Pd / Rh ratio was 0/55/5. The cell density of the substrate was 600 cells / in 2 and the wall thickness was about 4 mils (or 101.6 μm). The size of the substrate is 4.66 × 3 inches, volume was 51.17in ^3.

The lower layer deposited on the support contained palladium (Pd), a portion of which was supported by the ceria-zirconia oxygen storage component (OSC) and another portion supported by the high surface area gamma-alumina support. The lower layer also contained a barrier and zirconia. The load of the lower layer was 2.332 g / in ³ .

The upper layer deposited in the lower layer contained rhodium (Rh) on a commercially available La-ZrO ₂ support having a Lantana content of 9% by weight. The load on the upper layer was 1.403 g / in ³ .

Example 8
Test The formulated catalyst composites of Example 6 and Comparative Example 7 were aged at 950 ° C. for 5 hours in 10% water under a lean / overconcentrated cycle. Aged composites were tested with lambda sweep protocol at different temperatures (300 ° C, 350 ° C and 450 ° C). Conditions were as follows: GHSV = 15000 h ⁻¹ (standardized to 1 mL of coated catalyst) and vibration feed (λavg ± 0.025, 0.5 s dilute, 0.5 s overdense, 50 s / position) .

  The catalyst composite of Example 6 showed advantages for hydrocarbon (HC) conversion at 300 ° C to 350 ° C. FIG. 4 shows the conversion of hydrocarbon (HC) emissions for the blended catalyst composites of Example 6 and Comparative Example 7 under conditions of 300 ° C. to 350 ° C., particularly overrich conditions. There was no significant advantage above 400 ° C. As shown in FIG. 5, in the case of the conversion of carbon monoxide (CO), the catalyst composite of Example 6 showed an improvement at 300 ° C. to 350 ° C. In the case of nitrogen oxide (NO) conversion, there was no significant difference, but the test method of the catalyst itself could be a factor, i.e. the NOx conversion was too high, so the difference between the two catalysts (support material) It should be noted that it is not possible to distinguish between them.

  Throughout this specification, references to “one embodiment,” “an embodiment,” “one or more embodiments,” or “embodiments” refer to particular features, structures, It means that a material or property is included in at least one embodiment of the invention. Thus, the appearances of the phrases “in one or more embodiments”, “in one embodiment”, “in one embodiment”, or “in an embodiment” in various places throughout this specification are not necessarily the invention. Does not imply the same embodiment. Furthermore, the particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments.

  Although the present invention has been described with emphasis on preferred embodiments, preferred apparatus and method variations may be used, and the invention may be practiced otherwise than as specifically described herein. It will be apparent to those skilled in the art that it is intended to be good. Accordingly, this invention includes all modifications encompassed within the spirit and scope of the invention as defined by the following claims.

Claims (23)

A mixed metal oxide composite for exhaust gas purification catalyst, wherein the composite is
Zirconia in an amount ranging from 55 to 99% by weight;
Titania in an amount ranging from 1 to 25% by weight;
Said composite comprising an amount of cocatalyst and / or stabilizer in the range of 0-20% by weight, said composite being effective as a support for platinum group metals (PGM).   The composite of claim 1, wherein the promoter comprises a rare earth metal oxide and is present in an amount ranging from 0.1% to 20%.   The composite of claim 1, wherein the promoter comprises lantana, tungsta, ceria, neodymia, gadolinia, yttria, praseodymia, samaria, hafnia, or combinations thereof.   The composite of claim 1, wherein the stabilizer is present in an amount ranging from 0.1% to 5% and comprises silicon oxide.   The composite of claim 1, wherein the stabilizer is present in an amount ranging from 0.1% to 10% and comprises an alkaline earth metal oxide.   The composite material of Claim 1 whose ceria content rate is 20 mass% or less.   The composite according to claim 1, wherein the zirconia, the titania, and the promoter and / or the stabilizer are co-precipitated.   The composite according to claim 1, wherein the zirconia and the promoter and / or the stabilizer are co-precipitated and the titania is impregnated from a titania precursor.   The composite of claim 8, wherein the titania precursor comprises a titanium salt, a titanium-containing organic complex, a titania sol, or a colloidal titania. 12 hours at 1000 ° C., after aging in a furnace, having a surface area in the range of 10 to 40 m ² / g, the composite material according to claim 1.   A catalyst composite for treating an exhaust gas flow of a combustion engine, wherein the catalyst composite includes a catalyst material on a support, and the catalyst material is a composite metal oxide composite according to claim 1. The catalyst composite comprising platinum group metal (PGM) supported thereon. The mixed metal oxide composite contains zirconia in an amount in the range of 55-90% by weight; titania in an amount in the range of 5-25% by weight; lanthanum oxide in an amount in the range of 5-20% by weight. The catalyst composite of claim 11, comprising a catalyst; and the platinum group metal comprises rhodium.   12. The catalyst composite of claim 11 comprising rhodium in an amount ranging from 0.1% to 5% by weight.   12. The catalyst composite of claim 11 having a mass ratio of titania to rhodium in the range of 5 to 250.   After aging at 950 ° C., conversion of carbon monoxide, nitrogen oxides and hydrogen of 50% or more; and 10 for lambda in the range of 0.98 to 1.02 during a lean overconcentrated lambda sweep test at 300 ° C. 14. The catalyst composite of claim 13 comprising 0.25 wt% rhodium effective to provide a hydrocarbon conversion of greater than or equal to 100%. A system for treating an exhaust gas stream comprising hydrocarbons, carbon monoxide, and nitrogen oxides of an internal combustion engine,
This exhaust gas treatment system
12. An exhaust pipe in fluid communication with an internal combustion engine via an exhaust manifold; and the system comprising the catalyst composite of claim 11.   A method for treating exhaust gas comprising contacting a gas stream comprising hydrocarbons, carbon monoxide, and nitrogen oxides with the catalyst composite of claim 11. The mixed metal oxide composite contains zirconia in an amount in the range of 55-90% by weight; titania in an amount in the range of 5-25% by weight; lanthanum oxide in an amount in the range of 5-20% by weight. Containing a cocatalyst and the platinum group metal in an amount ranging from 0.1 to 5% by weight, for example 0.25% by weight rhodium; and after aging at 950 ° C., the catalyst composite is 50% Carbon monoxide, nitrogen oxides, and hydrogen conversion rates as described above; and hydrocarbon conversion rates of 10% or more with lambda in the range of 0.98 to 1.02 during the lean overconcentrated lambda sweep test at 300 ° C. The method of claim 17, wherein the method is effective to provide A method for producing a mixed metal oxide composite,
Obtaining or forming a first aqueous solution of a salt of zirconium, a salt of a metal promoter, and optionally a stabilizer;
Obtaining or forming a second aqueous solution of a salt of titanium;
Mixing the first aqueous solution with the second aqueous solution; and coprecipitating zirconium, an optional promoter or stabilizer metal, and titanium under basic conditions; thereby the mixed metal oxide coprecipitated Forming said composite material. The co-precipitated mixed metal oxide composite is
20. A process according to claim 19, comprising an amount of zirconia in the range of 55-99%; an amount of titania in the range of 1-25%; an amount of promoter and / or stabilizer in the range of 0-20%.   20. The method of claim 19, further comprising drying and firing the co-precipitated mixed metal oxide composite. A method for producing a mixed metal oxide composite,
Obtaining co-precipitated zirconia and metal promoters and optional stabilizers;
Obtaining an aqueous solution of a precursor of titanium;
Impregnating the coprecipitated zirconia and metal promoter with a precursor of titanium;
Forming said mixed metal oxide composite.   The mixed metal oxide composite comprises an amount of zirconia in the range of 55-99%; an amount of titania in the range of 1-25%; an amount of promoter and / or stabilizer in the range of 0-20%; The method of claim 22.

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